Heat your oven to 400 degrees F.
In a small bowl, stir together the sugar and orange zest. Set aside.
In a separate large mixing bowl, whisk together the flour, baking powder, and salt.
Grate or cut the cold butter into the flour mixture. Using a pastry fork, combine until the mixture becomes crumbly.
Make a well in the center of the mixture and pour in the buttermilk and one portion of the separated orange juice.
Add the sugar/zest mixture that was set aside previously.
Use your hands to combine the ingredients and form the dough into a ball. If the dough seems too sticky, add more flour ¼ cup at a time until no longer sticky.
Turn the dough out onto a floured surface and shape into a thick disc.
Pat or roll the dough to a thickness of about an inch.
Cut into 8 triangles (as if cutting a pie) and place them onto a lined baking sheet two inches apart.
Brush each scone with the remaining orange juice until the tops are lightly saturated.
Bake the scones for 12-15 minutes or until just slightly golden brown on the bottoms and baked through the middle.
Remove the baked scones to a cooling rack and allow them to cool completely.
In a medium bowl, whisk together the powdered sugar, orange juice, and orange zest until smooth.
Spoon over the cooled scones and serve.